Racing defeated Guarani 4-1 in Buenos Aires on Tuesday to move to six points in Group Eight, four clear of second-placed Sporting Cristal, with Bou backing up his treble away to Deportivo Tachira last week with another hat-trick.
Sporting were held to a 1-1 draw at home by Tachira.
A howler from Guarani goalkeeper Alfredo Aguilar allowed Bou to open the scoring in the 44th minute with the 25-year-old striker's 20-yard strike squeezing through the gloveman's hands.
It was 2-0 soon after the break with Bou teeing up Diego Milito for a simple finish from less than 10 yards, while Federico Santander dragged a goal back with 25 minutes remaining.
Racing regained their two-goal cushion in the 79th minute, with Bou converting from Brian Fernandez's cross.
The home side moved three goals ahead three minutes later when Bou struck another first-time shot past Aguilar from Washington Camacho's centre.
Emelec also claimed a big win on Tuesday as Miller Bolanos, Mauro Fernandez and Angel Mena scored in the Ecuadorian club's 3-0 triumph over The Strongest.
The victory took Emelec to six points, three clear of their Bolivian opponents, while the other two clubs in Group Four - Universidad de Chile and Internacional - have zero points but are yet to play their second game.
In Argentina, Huracan came from behind twice to draw 2-2 with visiting Mineros de Guayana.
